Population Structure and Life Table of the Endangered Population of Taxus yunnanensis

Taxus yunnanensis Cheng et L. is an endangered evergreen conifer and important protected plant of China. There haven't comprehensive investigations on its population. In this paper, 14 plots with 5 600 m2 were investigated, and field data were obtained. The age and structure of the population was analyzed. The time-specific life table, the curves of survivorship, mortality rate, hazard and the four survival function of the population were drawn. The results showed that the numbers of the Taxus yunnanensis population was is very limited, and had an obvious period fluctuation companying the growth of the population. It was convinced that the age structure analysis was much more reasonable than the size class method used widely at present. Its survival curve could be described by Deevey-Ⅲ. The mortality ratio curve showed the similar dynamics to hazard curve. The population had 2 distinct peaks of mortality, 100 a to 130 a and 230 a to 250 a, respectively. The first peak was due to serve environment. Generally, the population grew up stable in the early age, and then went into the middle age which the number of population decreased very quickly, followed by a decline old age. Its mortality rate will exceed 95% and survival rate will decrease to below 5% after 160 a-190 a.